1. Field of the Invention
The present invention relates to an improved toner dispensing apparatus for electrophotographic copiers.
2. Description of the Prior Art
In commonly assigned U.S. patent application, Ser. No. 542,319 of Charles E. Myers and James E. Genthe filed on Jan. 20, 1975 and entitled "Toner Dispensing Apparatus", an apparatus for adding fresh toner to the cascade development system of an electrophotographic copier is described. As set forth in that application, the dispensing apparatus includes an elongated hollow tubular member positioned within and extending across the developer housing together with a toner supply container supported exteriorly of the developer housing. In addition, a rotatable auger of novel construction having a helical channel formed around its surface is positioned within both the tubular member and the supply container and is adapted to pick up fresh toner from the supply container and transport it into and along the tubular member to be automatically dispensed in precise amounts through a plurality of apertures extending along the bottom of the tubular member.
Although this system has proven to be quite effective in dispensing metered amounts of toner into the developer housing, investigations have shown that certain modifications are desirable to make it practical for use in a commercial copier. In particular, to be suitable for use in a convenience copier, it is highly desirable that the dispenser be designed to permit easy replacement or refilling of the toner supply housing when it becomes exhausted so that this activity may be carried out by untrained personnel with a minimum of machine down-time. Also, it is important that toner replenishment be accomplished in a manner that will minimize the danger of toner spillage as this cannot only contaminate the environment, but can also clog or damage parts of the machine itself. Finally, to accomplish the above goals, it is preferred that the toner supply housing portion of the dispenser be replaced in its entirety when it becomes depleted of toner, and this makes it important to keep the cost of the components within the toner supply housing as low as possible without sacrificing reliability.